Reconstructions and analyses from the Lichtman laboratory at Harvard University and Connectomics group at Google H01 human cortex serial EM volume.
Attribution and data: https://h01-release.storage.googleapis.com/data.html
Citation: https://h01-release.storage.googleapis.com/paper.html
Two mitochondria appear to be in the end stages of fission. Viewing the z-plane above and below the current plane of focus shows that there is a thin bit of membrane connecting the two mitochondria together. Mitochondria are dynamic, moving along the cytoskeleton, fusing together and breaking apart. This dynamic transition is frozen in time here in this fixed electron micrograph.